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David Howells 378831e4da afs: Fix directory permissions check
Doing faccessat("/afs/some/directory", 0) triggers a BUG in the permissions
check code.

Fix this by just removing the BUG section.  If no permissions are asked
for, just return okay if the file exists.

Also:

 (1) Split up the directory check so that it has separate if-statements
     rather than if-else-if (e.g. checking for MAY_EXEC shouldn't skip the
     check for MAY_READ and MAY_WRITE).

 (2) Check for MAY_CHDIR as MAY_EXEC.

Without the main fix, the following BUG may occur:

 kernel BUG at fs/afs/security.c:386!
 invalid opcode: 0000 [#1] SMP PTI
 ...
 RIP: 0010:afs_permission+0x19d/0x1a0 [kafs]
 ...
 Call Trace:
  ? inode_permission+0xbe/0x180
  ? do_faccessat+0xdc/0x270
  ? do_syscall_64+0x60/0x1f0
  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: 00d3b7a453 ("[AFS]: Add security support.")
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Signed-off-by: David Howells <dhowells@redhat.com>
2018-05-16 21:35:23 +01:00
arch Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:53:08 -07:00
block blk-mq: fix sysfs inflight counter 2018-04-26 09:02:01 -06:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto crypto: drbg - set freed buffers to NULL 2018-04-21 00:57:00 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
drivers SCSI fixes on 20180515 2018-05-15 10:15:48 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs afs: Fix directory permissions check 2018-05-16 21:35:23 +01:00
include AFS fixes 2018-05-15 10:48:36 -07:00
init init: fix false positives in W+X checking 2018-05-11 17:28:45 -07:00
ipc ipc/shm: fix use-after-free of shm file via remap_file_pages() 2018-04-13 17:10:27 -07:00
kernel Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:53:08 -07:00
lib another dma-mapping fix for 4.17-rc: 2018-05-13 10:28:53 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
samples bpf: sockmap sample use clang flag, -target bpf 2018-04-23 23:42:21 +02:00
scripts scripts/faddr2line: fix error when addr2line output contains discriminator 2018-05-11 17:28:45 -07:00
security Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-24 17:58:51 -07:00
sound ALSA: pcm: Check PCM state at xfern compat ioctl 2018-05-02 08:54:54 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-13 10:44:32 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM/arm fixes for 4.17, take #2 2018-05-05 23:05:31 +02:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge candidates for 4.17 merge window 2018-04-06 17:35:43 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
Makefile Linux 4.17-rc5 2018-05-13 16:15:17 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.